In 1887, he published "On the Scope and Methods of Geography", a manifesto for the New Geography.[3] A few months later, he was appointed as Reader in Geography at the University of Oxford, where he introduced the teaching of the subject. As Mackinder himself put it, "a platform has been given to a geographer". This was arguably at the time the most prestigious academic position for a British geographer.

In 1892, he was the first Principal of University Extension College, Reading, a role he retained until he was succeeded, in 1903, by William Macbride Childs. The college became the University of Reading in 1926, a progression that owed no small debt to his early stewardship of the institution.[4][5]

In 1893, he was one of the founders of the Geographical Association, which promotes the teaching of geography in schools. He later became chairman of the GA from 1913 to 1946 and served as its President from 1916.

In 1895, he was one of the founders of the London School of Economics. At Oxford, Mackinder was the driving force behind the creation of a School of Geography in 1899.[6] In the same year, he led an expedition which was the first to climb Mount Kenya.[7]

In 1902 he published Britain and the British Seas, which included the first comprehensive geomorphology of the British Isles and which became a classic in regional geography.[8]

His next major work, Democratic Ideals and Reality: A Study in the Politics of Reconstruction, appeared in 1919.[14] It presented his theory of the Heartland and made a case for fully taking into account geopolitical factors at the Paris Peace conference and contrasted (geographical) reality with Woodrow Wilson's idealism. The book's most famous quote was: "Who rules East Europe commands the Heartland; Who rules the Heartland commands the World Island; Who rules the World Island commands the World." This message was composed to convince the world statesmen at the Paris Peace conference of the crucial importance of Eastern Europe as the strategic route to the Heartland was interpreted as requiring a strip of buffer state to separate Germany and Russia. These were created by the peace negotiators but proved to be ineffective bulwarks in 1939 (although this may be seen as a failure of other, later statesmen during the interbellum). The principal concern of his work was to warn of the possibility of another major war (a warning also given by economist John Maynard Keynes).

Mackinder was anti-Bolshevik, and as British High Commissioner in Southern Russia in late 1919 and early 1920, he stressed the need for Britain to continue her support to the White Russian forces, which he attempted to unite.[15]

Mackinder's work paved the way for the establishment of geography as a distinct discipline in the United Kingdom. His role in fostering the teaching of geography is probably greater than that of any other single British geographer.

Mackinder, H.J. "Man-Power as a Measure of National and Imperial Strength", National and English Review, XIV, 1905.

Mackinder, HJ. "Geography and History", The Times. 9 February 1905.

Mackinder, H.J. as editor of The Regions of the World series which includes the 1902 Britain and the British Seas mentioned above—which included The Nearer East by D.G. Hogarth London, Henry Frowde, 1902 and 1905

Mackinder, HJ. 1943. "The round world and the winning of the peace", Foreign Affairs, 21 (1943) 595–605. Available online as Mackinder, H.J. "The round world and the winning of the peace", in Democratic Ideals and Reality, Washington, DC: National Defence University Press, 1996, pp. 195–205.

^Ian Macrae, "The making of a university, the breakdown of a movement: Reading University Extension College to The University of Reading, 1892–1925", Journal International Journal of Lifelong Education, Volume 13, Issue 1 January 1994, pages 3–18